Re: Four Bars per Line/System, again :)

[David Nalesnik]

Hi Michael,

On Sun, Jan 25, 2015 at 2:11 PM, Michael Hendry <address@hidden> wrote:

Thanks, David.

I'm very much at the stage of using example files and modifying them so that
they work for me as far as Lilypond is concerned - and can't even plod
through your Scheme function definition to work out what it's doing!

4 bars per line or 8 bars per line will do everything I want - the reason I
started investigating further is that the...

\repeat unfold 3 {
          s1 \noBreak s1 \noBreak s1 \noBreak s1 \break }

...trick I'd been using up to now had caused a problem with the leadsheet
for a song I was working on - it produced an extra blank stave, which I
couldn't get rid of until I came across your function.

Any chance of your documenting its inner workings for a Scheme virgin?

Hmm..  the bars-per-line-engraver could use a comment of two explaining what it's doing.  Horizontal spacing is controlled by "paper columns" (PaperColumn and NonMusicalPaperColumn).   For line-breaking I'm interested in NonMusicalPaperColumns, because those are associated with line beginnings and endings.  They have a property called 'line-break-permission, set to 'allow by default.  Setting this property to 'force creates a line break.  (Well, if LilyPond decides it's a reasonable break--unless you use the override discussed earlier in the thread.)  So, this engraver changes the 'line-break-permission property to 'force to achieve the proper measures per line.  (By the way, there's an enhancement--not sure if it made it out of a private thread--which sets bars per line and systems per page.  I'll have to look around.)

Now as far as what a "Scheme engraver" is, I'm hoping to create some sort of tutorial on the Scores of Beauty site.  Could be a while, though!  I will say, though, that if you want an intro to Scheme you should definitely start with the Extending manual.  That would be more helpful than trying to tease out this engraver (which is a bit obscure).

--David